Hollow structure for fuel

Abstract

Provided is a hollow structure for fuel, in which a conductive layer containing a fluororesin is used; that is excellent in fuel barrier properties and low-temperature impact resistance, and further is excellent in interlayer adhesion,The hollow structure for fuel includes a polyamide rein layer (A) a polyamide resin layer (B), a polyamide resin layer (C), and a conductive layer (D) in this order from an outside. The polyamide resin layer (A) contains a polyamide resin (a). The polyamide resin layer (B) contains a polyolefin, a polyamide resin (b1) containing a structural unit derived from metaxylylenediamine and a structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms, and a polyamide resin (b2) containing a structural unit derived from xylylenediamine and a structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms. The polyamide resin layer (C) contains a polyamide resin (c). The conductive layer (D) contains a fluororesin and a conductive substance.

1 . A hollow structure for fuel, comprising a polyamide resin layer (A), a polyamide resin layer (B), a polyamide resin layer (C), and a conductive layer (D) in this order from an outside,
 wherein the polyamide resin layer (A) comprises a polyamide resin (a), 90 mol % or more of all structural units of the polyamide resin (a) being one or more of: a structural unit derived from a lactam having from 10 to 12 carbon atoms; a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms; a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms; and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms,   wherein the polyamide resin layer (B) comprises a polyolefin, a polyamide resin (b1), and a polyamide resin (b2); a content of the polyolefin is from 5 to 40 mass % of the polyamide resin layer (B); a mass ratio (b1/b2) between a content of the polyamide resin (b1) and a content of the polyamide resin (b2) is from 55/45 to 95/5, the polyamide resin (b1) comprising: a diamine-derived structural unit containing 70 mol % or more of a structural unit derived from metaxylylenediamine; and a dicarboxylic acid-derived structural unit containing 70 mol % or more of a structural unit derived from an aliphatic dicarboxylic acid having from 4 to 8 carbon atoms, the polyamide resin (b2) comprising: a diamine-derived structural unit containing 70 mol % or more of a structural unit derived from xylylenediamine; and a dicarboxylic acid-derived structural unit containing 70 mol % or more of a structural unit derived from an aliphatic dicarboxylic acid having from 9 to 12 carbon atoms,   wherein the polyamide resin layer (C) comprises a polyamide resin (c), 90 mol % or more of all structural units of the polyamide resin (c) being one or more of: a structural unit derived from a lactam having from 10 to 12 carbon atoms; a structural unit derived from an aminocarboxylic acid having from 10 to 12 carbon atoms; a structural unit derived from an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms; and a structural unit derived from an aliphatic diamine having from 6 to 12 carbon atoms, and   wherein the conductive layer (D) comprises a fluororesin and a conductive substance.   
     
     
         2 . The hollow structure for fuel according to  claim 1 , wherein the polyamide resin layer (A) comprises a polyolefin. 
     
     
         3 . The hollow structure for fuel according to  claim 2 , wherein the polyolefin contained in the polyamide resin layer (A) and the polyolefin contained in the polyamide resin layer (B) are each an acid-modified polyolefin. 
     
     
         4 . The hollow structure for fuel according to  claim 1 , wherein a content of the polyolefin contained in the polyamide resin layer (C) is from 0 to 7 mass %. 
     
     
         5 . The hollow structure for fuel according to  claim 1 , wherein a thickness of the layer (A)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (A) to the thickness of the polyamide resin layer (C), is from 3.0 to 9.0 times, and a thickness of the layer (B)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (B) to the thickness of the polyamide resin layer (C), is from 1.0 to 3.0 times. 
     
     
         6 . The hollow structure for fuel according to  claim 5 , wherein the polyamide resin layer (A) comprises a polyolefin, each polyolefin contained in the polyamide resin layer (A) and the polyamide resin layer (B) is an acid-modified polyolefin, and a content of the polyolefin contained in the polyamide resin layer (C) is from 0 to 7 mass %. 
     
     
         7 . The hollow structure for fuel according to  claim 1 , wherein, in the polyamide resin layer (B), a total of the polyolefin, the polyamide resin (b1), and the polyamide resin (b2) accounts for more than 95 mass % of the polyamide resin layer (B). 
     
     
         8 . The hollow structure for fuel according to  claim 1 , wherein the fluororesin comprises a fluoroethylene (co)polymer. 
     
     
         9 . The hollow structure for fuel according to  claim 1 , wherein the fluororesin comprises an ethylene/fluoroethylene propylene copolymer. 
     
     
         10 . The hollow structure for fuel according to  claim 1 , wherein the conductive substance comprises a conductive carbon compound. 
     
     
         11 . The hollow structure for fuel according to  claim 1 , wherein the polyamide resin layer (A) comprises a plasticizer in a proportion of from 1 to 20 mass % in the polyamide resin layer (A). 
     
     
         12 . The hollow structure for fuel according to  claim 1 , wherein the polyamide resin layer (C) comprises a plasticizer in a proportion of from 1 to 20 mass % in the polyamide resin layer (C). 
     
     
         13 . The hollow structure for fuel according to  claim 2 , wherein a content of the polyolefin contained in the polyamide resin layer (C) is from 0 to 7 mass %. 
     
     
         14 . The hollow structure for fuel according to  claim 2 , wherein a thickness of the layer (A)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (A) to the thickness of the polyamide resin layer (C), is from 3.0 to 9.0 times, and a thickness of the layer (B)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (B) to the thickness of the polyamide resin layer (C), is from 1.0 to 3.0 times. 
     
     
         15 . The hollow structure for fuel according to  claim 14 , wherein the polyamide resin layer (A) comprises a polyolefin, each polyolefin contained in the polyamide resin layer (A) and the polyamide resin layer (B) is an acid-modified polyolefin, and a content of the polyolefin contained in the polyamide resin layer (C) is from 0 to 7 mass %. 
     
     
         16 . The hollow structure for fuel according to  claim 2 , wherein, in the polyamide resin layer (B), a total of the polyolefin, the polyamide resin (b1), and the polyamide resin (b2) accounts for more than 95 mass % of the polyamide resin layer (B). 
     
     
         17 . The hollow structure for fuel according to  claim 2 , wherein the fluororesin comprises a fluoroethylene (co)polymer. 
     
     
         18 . The hollow structure for fuel according to  claim 2 , wherein the fluororesin comprises an ethylene/fluoroethylene propylene copolymer. 
     
     
         19 . The hollow structure for fuel according to  claim 2 , wherein the conductive substance comprises a conductive carbon compound. 
     
     
         20 . The hollow structure for fuel according to  claim 3 , wherein a content of the polyolefin contained in the polyamide resin layer (C) is from 0 to 7 mass %;
 a thickness of the layer (A)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (A) to the thickness of the polyamide resin layer (C), is from 3.0 to 9.0 times, and a thickness of the layer (B)/a thickness of the layer (C), which is a ratio of the thickness of the polyamide resin layer (B) to the thickness of the polyamide resin layer (C), is from 1.0 to 3.0 times;   in the polyamide resin layer (B), a total of the polyolefin, the polyamide resin (b1), and the polyamide resin (b2) accounts for more than 95 mass % of the polyamide resin layer (B);   the fluororesin comprises an ethylene/fluoroethylene propylene copolymer;   the conductive substance comprises a conductive carbon compound; and   the polyamide resin layer (A) comprises a plasticizer in a proportion of from 1 to 20 mass % in the polyamide resin layer (A).